Powder processing for 3D printing
Additive manufacturing enables unusual shapes, makes small series more cost-effective and speeds up production. The 3D printer itself is only one link in the production chain - from delivery of the raw materials to post-processing of the components. Screening, mixing and conveying technology, dryers, safety equipment, particle analytics and more complement 3D printers to create high-performance AM solutions.
Additive manufacturing as a professional application of 3D printing is regarded in numerous industries as a revolutionary method of manufacturing products such as components with complex shapes. It even allows customisation without the need for additional moulds or tools, for example for medical prostheses. As a material-saving process, it is also suitable for expensive materials such as titanium. Its applications range from medicine, mechanical engineering, ceramics and the automotive industry to the construction industry. Even houses and bridges can be produced using 3D printing.
Additive processes permeate POWTECH TECHNOPHARM
Additive manufacturing is also increasingly becoming a key technology for the POWTECH TECHNOPHARM community. For example, the APV, the International Association for Pharmaceutical Technology, has already established an Additive Manufacturing Task Force. Over 40 members from various pharmaceutical companies, including Merck, Novartis and Sanofi-Aventis, as well as from scientific institutions are dedicated to topics such as batch production and individualised manufacturing via AM. Other conceptual sponsors of the trade fair have long been involved with this innovative manufacturing method, such as the VDI Wissensforum, which offers numerous seminars on the subject, and the VDMA, which has produced a pioneering position paper.
The PARTEC science congress, which will once again take place alongside POWTECH TECHNOPHARM in 2025, will also focus on additive manufacturing processes, in particular the aspect of particle technology and its impact on 3D printing. As in 2023, the expert forums in the exhibition halls will once again provide insights into the possibilities and requirements of additive manufacturing.
Additive manufacturing processes enable moulds that were previously very difficult to produce.Numerous core processes of powder and particle technology play a role, particularly in the preparation of starting products, their qualification and feeding to the actual 3D printer. The printing process and materials used determine what is important.
In selective laser sintering (SLS), for example, the starting products are in powder form. The materials used include metal powders such as aluminium and titanium, silicon carbide, thermoplastic polyurethane and polyamide. The SLS powders must have a uniform, relatively small particle size. They are dried and sieved before processing to ensure a homogeneous grain size.
The material requirements for the DED (Directed Energy Deposition) process using metal or ceramic powder are similar. The starting products can be explosive; explosion protection measures are therefore often required.
The classic screening technology is used in adapted variants. For example, the company assonic Dorstener Siebtechnik offers special machines for the ultrasound-assisted screening of fine metal and plastic powders, starting with mesh sizes of 20 µm. The Sonic Speed Screen screening technology works with a combination of high-frequency ultrasound and low-frequency knocker excitation. This enables a high screening capacity to be realised with a small footprint. The Sonic Powder Conditioner can be used to automate metal sieving and preparation for additive manufacturing. The Mini Sonic Screen MSS 150 can also be used for batch processing of small quantities of powder.
If the starting products are thermoplastic filaments such as PLA or ABS, careful drying is required, as with powders. Otherwise, bubbles may form in common printing processes such as fused filament fabrication (FFF). The filaments may also need to be cut to the correct length before printing.
Liquid starting products such as resins used in stereolithography or digital light processing, must also be prepared before printing. Pigments and additives are evenly distributed by shaking or stirring. Impurities are removed by filtration.
Carefully analyse material properties
Quality control is very important in all preparatory processes. Foreign substances that could impair the print quality and durability of the parts to be produced must be removed. In addition to the particle size, the chemical properties and moisture content of the material are also checked. Specialised trade fair exhibitors such as AZO already provide support during the development of 3D printing processes. The company's Technology Centre includes a so-called Toxicontainer. It enables the safe testing of hazardous raw materials used in additive manufacturing. In this safe test room with PPE, glovebox and special air filter system, the materials can be tested under optimal conditions, ensuring maximum protection for the product and operator. AZO also offers a wide range of solutions for the storage, conveying, feeding, conditioning and recovery of plastic and metal materials for additive manufacturing.
After correct preparation and quality control, the material is fed to the printers, for example using special dosing systems for powder feeding. They must ensure an uninterrupted supply to the 3D printers. The product is added via a glovebox, for example, and conveyed under inert gas. Pneumatic and vibration processes, screw conveyor systems and powder nozzles are used here. Resins, on the other hand, are sometimes fed to the printer build chambers via pump systems. A sieve module is usually installed upstream of the actual pressure chamber.
Thinking about safety aspects
IB Verfahrenstechnik, a member of the PIAB Group since 2023, specialises in material flow technology in 3D printing production. IB Additive brand solutions are created from an extensive modular system of ultrasonic screening stations and vacuum conveyors. Thanks to their modularity, existing systems can be easily converted or expanded. Integrated inertisation and residual oxygen monitoring complement the main modules.
The compact ECODustPro 15 WB inert safety vacuum cleaner from Evo Products is also designed for safety in additive manufacturing. Extracted explosive metal dusts are passivated by a liquid bath. The full range of safety features includes a degassing valve, which prevents the build-up of gases and vapours, as well as graduated filtration using H14 cartridge filters and special VA filters. Ex protection is guaranteed in Zone 22.
Process Sensing Technologies PST is addressing another safety aspect with the compact Ntron SIL-O2 oxygen analyser. As a SIL2 device, it is particularly suitable for safety-critical applications. It can be calibrated at the touch of a button and is ready for easy integration.
Perfect coordination between AM and powder handling system
Partnerships between bulk material handling experts and 3D printer manufacturers, such as Volkmann and EOS, are particularly beneficial for the end customer. Together, they have developed a scalable powder handling solution for metal powder that can supply up to six printers. In addition to pre-processing, the solution also includes post-processing, including the preparation of used powder through sieving. This makes it possible to realise a closed powder cycle for fully automatic 24/7 operation. The end user benefits from a single point of contact throughout the entire life cycle of their system and from harmonised AM and powder handling systems.
Partial view of the 3D printing production line at BMW; in the background the Volkmann depowdering module.Volkmann offers a wide range of products especially for conveying metal powders in additive manufacturing. Closed powder loops and a high degree of automation can thus be achieved. The company is also represented at the BMW Group Additive Manufacturing Campus in Oberschleissheim near Munick with its machines for centralised powder preparation. The system there was developed as part of the IDAM (Industrialisation and Digitalisation of Additive Manufacturing) research project. After the 3D printing process, residual powder is collected. These are reconditioned and reused as a mixture with the primary starting materials, particularly in the case of expensive materials.
Recycling valuable materials after depowdering
Other process technologies from the POWTECH-TECHNOPHARM range can be used in the final process step, such as vibrating screens like the Cuccolini 3D 500 screen, which enables the simple and practical recovery of metal powders. The manufacturer offers it with various additional packages, such as a collection container, solutions for gas inertisation and for process control.
The powder preparation units from Telsonic are also useful in the process step after the actual printing. They screen out clumps and other impurities using ultrasound. With a separation efficiency of almost 99 per cent, they separate the reusable good particles from the oversized particles. Such powder processing units can be integrated into the 3D printer, attached externally or used as standalone systems.
In addition to the expertise of the manufacturers of process engineering machines, developers of 3D printing processes can also utilise the services of service companies such as GMBU e.V. (Gesellschaft zur Förderung von Medizin-, Bio- und Umwelttechnologien: Society for the Promotion of Medical, Bio and Environmental Technologies). In the field of additive manufacturing, the society develops and evaluates processes for quality assurance, functional prototypes and materials such as filaments and granulates (e.g. bio-based, microfibre-reinforced, foamable or recyclate-based). If required, it can also produce these on a laboratory scale. This means that, in addition to designers of 3D printing solutions, developers of suitable materials and end users from various industries will also find contacts and experts at POWTECH TECHNOPHARM to support them in their endeavours.
